QR code basics

QR code error correction explained

QR codes include spare information that can help a phone read the code when a small part is damaged or covered. It is useful, but it is not a licence to make the code difficult to scan.

What error correction actually does

A QR code contains redundant data alongside its main content. If a small part of the pattern is damaged, dirty, or carefully covered by a logo, a scanner may still be able to reconstruct the missing information. This is called error correction.

It does not fix a broken destination, make a low-contrast code visible, or compensate for a missing quiet zone. It only helps the scanner recover from limited damage to the pattern itself.

The four error-correction levels

LevelWhat it meansWhen it is useful
LLower redundancy, simpler patternClean, high-quality codes where space matters and there is no logo.
MBalanced redundancyA sensible general-purpose choice for many standard QR codes.
QHigher redundancyCodes that may face modest wear or a small, carefully tested logo.
HHighest redundancyA code with more damage risk or a logo, only after testing the final design.

More error correction creates a denser QR code

The trade-off is simple: more recovery data means a more complex pattern. If you put a long URL, a large amount of text, or detailed contact information into the code, higher error correction can make the individual modules smaller and harder to scan at a given physical size.

That is why there is no universally best level. The right choice depends on how much content the code holds, how large it will print, whether it has a logo, and where people will scan it.

Use error correction well

Keep logos small and centred

A logo belongs in the central area, not over the three finder patterns in the corners. Leave enough clear space around it and test the finished code.

Do not hide the important parts

Frames, labels, stickers, folds, and decorative overlays can damage the pattern just as easily as a logo can.

Use the shortest practical content

A concise URL produces a simpler, more forgiving pattern than a long URL with unnecessary parameters or a large block of text.

Test after every visual change

Changing colour, logo size, export format, or print material can change scan reliability. The final proof is the only test that matters.

What error correction cannot rescue

These issues need a design or production fix, not a higher setting.

  • โ†’Light modules on a light background, or any other weak contrast combination.
  • โ†’A quiet zone that is cropped away or filled with text, a border, or an image.
  • โ†’A code printed too small for the distance from which people must scan it.
  • โ†’A heavily distorted, stretched, or compressed QR image.
  • โ†’A destination page that no longer exists or does not work well on a phone.

Create a QR code, then test the version people will scan.